It makes complete sense. Currently the Air Force sends out emails notifying the interested parties of a possible collision, and then the parties hash it out over email. It's clearly not a sustainable model as LEO traffic grows.

There are quite many air traffic controlllers and they actually do something. Watching satellites is like watching paint to dry. You need to do complex calculations and most if the time result is, almost zero change of collision

SpaceX already have automated collision avoidance for Starlink satellites. Apparently they've taken 14 avoiding actions since initial deployment. Have to wonder how Satellite 44 would have handled this issue without human intervention. Overall seems unlikely ESA will be allowed access to Starlink, just have to find better way to communicate with SpaceX.

Even if the manoeuvre was automatic, it would still need communication between the operators of the two (or in the future, potentially more) satellites to determine who is going to move where. Otherwise, you could just end up moving out of one intersection and into another.

I'm sure you're aware but i must add that hose warnings would be correct if both aircraft have TCAS and follow their individual instructions on which way to change course. Otherwise we risk the 2002 uberlingen disaster

Like when you're walking towards someone in a hallway, and they move to their left just as you move to your right, so then you both correct, and you both just end up weaving back and forth synchronized, until you collide or come to a dead stop. Only with satellites.

The thing I don’t get is that ESA is a major, multi-governmental agency. If they really thought this was an urgent situation (a “near disaster” as jerk Greg Wyler described it), they surely could have contacted SpaceX. Just because one line of communication was buggy doesn’t mean they had no way to contact them. Does anyone really think that SpaceX would have ignored a phone call—hell, even a Tweet or a Facebook post—from the head of ESA?

This whole thing stinks to high Heaven of FUD. It’s so frickin’ obvious.

They did, and SpaceX said they weren't going to take action (based on data at the time that said action wasn't necessary). Also, who on Earth would be the SpaceX contact person for tweets about potential orbit conflicts? That's absolutely bizarre, and it should be completely unnecessary for the head of the ESA to be taking that approach.

This whole thing stinks to high Heaven of FUD

FUD where the public line from the ESA was "this situation was no one's fault"? I think you might need to refresh your definition of what FUD is.

"About a week ago" - data by the 18th Space Control Squadron of the US Air Force suggested a potential 'conjunction' between Starlink44 and Aeolus on Monday, September 2nd, 11:02 UTC (ESA press release)

Wednesday, August 28 - as the probability of collision increased, ESA reached out to SpaceX to 'discuss options', SpaceX reacted within a day to express that they would not move their satellite (ESA press release); the probability of collision was about 2.2e-5 (~ 1 in 50k) at the time, so both SpaceX and ESA decided action was unnecessary, this was the last contact between SpaceX and ESA (SpaceX statement/Loren Grush on Twitter)

Thursday, August 29 - as the probability passed the threshold of 1e-4 (1 in 10k) (in the evening), ESA prepared a manoeuvre raising Aeolus' orbit by ~350m to pass over Starlink44 (ESA press release); a bug in SpaceX' 'on-call paging system' lead to the Starlink operators being unable to notice this change (SpaceX statement/Loren Grush on Twitter)

Sunday, September 1 - as the probability continued to increase, ESA decided to go ahead with the avoidance manoeuvre and the commands were send to ESA's mission control center in Germany (ESA press release)

ESA released their press release, completely relieving SpaceX and 'thanking' for good communication (no time on the ESA website)

1 Please correct me on the time of the tweet, for me it says 7:36 am on September 2nd and, as I use MESZ currently, this is the UTC timing, which seems odd, as it indicates the manoeuvre was in the past already

So my TLDR would be: Much FUD about nothing. SpaceX and ESA had great communication when the change was below the threshold, but SpaceX did not notice the increase above the threshold due to a bug. ESA moved their satellite, put out some tweets and 'anonymous sources' and Starlink sceptics speculated the satellites out of the sky.

Contact with Starlink early in the process allowed ESA to take conflict-free action later, knowing the second spacecraft would remain where models expected it to be.

This indicated that the decision not to move Starlink44 was not just a passive response due to lack of a notification, but an active and negotiated course of action to allow Aeolus to manoeuvre without risk of moving into a new intercept.

If SpaceX wanted to move Starlink44, they would have to contact ESA again. (not written by law or anything, but every other course of action would be completely irresponsible)

So SpaceX's (and ESA's) decision to not move Starlink44 was not to allow Aeolus to manoeuvre without risk but rather due to old data indicating action would be unnecessary. But because there was no new information, this remained the standpoint ESA worked with.

​

Without earlier communication, ESA could not have been sure whether SpaceX planned a manoeuvre or not.

Before updating satellite course a company has to contact JSpOC in order to update the database. It is in the rules of using this database and JSpOC services.

Also they need to contact other party (if the satellite is operational) in order to coordinate avoidance maneuvers.

Plain common sense requires that. Nobody wants "british and french" on a common road thing.

There are yet no general avoidance rules in space.

Whole issue is blown out of proportions. "It's quite possible" (c) they were passing each other at the distance of more than 3.5km.

350m attitude correction avoidance maneuver executed in 3 rounds fully corresponds to the Aeolus orbital correction maneuvers she has to do regularly (operational life of this satellite is only 3 years, and the chances are very big that she won't survive 2).

The issue ESA has raised is very important one. But the choice of the "opponent" and the satellite in question (Aeolus is a epitaph on "why ESA sucks" tombstone) are very much most stupid choices they could pick from.

Well, to finally solve this we would have to ask someone who actually knows, but for now we are limited to interpreting every word in their statement ;-D

[...] prevented the Starlink operator from seeing the follow on correspondence on this probability increase [...]

This actually sounds like they were hindered from contacting ESA, but I think this is very unlikely. Even if their IT infrastructure fails they could still call them on the phone or get in touch in many other ways.

However, had the Starlink operator seen the correspondence, we would have coordinated with ESA to determine best approach with their continuing their maneuver or our performing a maneuver.

On first reading I thought this indicated a time progression: if they saw the probability increase they would then cooperate with ESA about the matter. But upon copying this statement, the 'their continuing their maneuver' sounds more like the maneuver proposal sent by ESA was overlooked.

This Air Force statement sadly doesn't clear things up, but the answer could be in the difference of messages received: SpaceX received 3 warnings less than ESA, which could either mean that they subscribed to less messages, or they did not receive three of the warnings (maybe a warning is 'received' when the recipient sends an email back acknowleding the warning?)

In the end, we can't say what happened if there are no more precise statements. But I see no reason why the Starlink operator should be able to see the dramatic increase to 1 in 600 but then not contact ESA to plan further actions, especially with 4 days between the increase and the actual close approach.

...prevented the Starlink operator from seeing the follow on correspondence on this probability increase...

To me it sounds like SpaceX was copied the correspondence between ESA and the Air Force but failed to see it due to their software problem.

In any case it probably made sense for Aeolus to move. It has bigger engines and has to make periodic orbit-raising maneuvers anyway in order to operate at that altitude. Starlink 44 has feeble ion thrusters and is being de-orbited because it is defective: it might not respond reliably to commands.

As days passed, the probability of collision continued to increase, and by Wednesday 28 August the team decided to reach out to Starlink to discuss their options. Within a day, the Starlink team informed ESA that they had no plan to take action at this point.

Can someone explain how this would happen? Are the models not very reliable or are there variables that change? Maybe atmospheric density changes over time can cause a skew? What variables are there that would change the probability?

I think this is due to uncertainty in satellite's orbital paths. Due to changes in atmospheric drag, tiny measurement errors and other related effects, the initial calculation gave a smaller probability.

This does not mean that the first calculation was wrong, it only means that it had more possible outcomes which were 'no crash' that were later ruled out due to new data.

Imagine dropping something from the Burj Khalifa. When you throw it, you only have a rough idea where it will land, so the probability for all places it could land is way smaller than 0.1. But the closer it gets to the ground, the more accurate the predictions are. So the probability didn't really increase by a few orders of magnitude, only 49,000 now-impossible cases got ruled out, while the one collision-case stayed in the possible-list.

This image shows how impact probability can rapidly increase and subsequently decrease as the trajectory of an object is increasingly refined.

For satellites, the ellipse of possible close passes will be in the square kilometer range, whereas the satellite itself spans mere meters. As the impact ellipse is shrunk, the probability of collision will rocket as the target satellite covers more and more of the shrinking ellipse, up until the ellipse shrinks enough to exclude the target satellite. Except in this case the ESA decided to move the satellite first, so we don't know whether that would have happened.

Error increases quickly over time, in numerical simulations. A difference of a few millionths quickly expands to a complete lack of precision, because the same happens in real life -- orbits are very dynamical. As such, numerical simulations are constantly recalibrated with observational data.

Also, those who were accusing anyone who was suspicious of ESA’s motives of being fanboys/Elon worshippers who think SpaceX can do no wrong...they should probably apologize as well.

Because honestly, any negative story about SpaceX (or Musk’s other ventures) absolutely should be viewed with lots of suspicion and skepticism, because they almost always do turn out to be FUD. You almost have to be delusional at this point not to strongly suspect that any such story is FUD!

What for? SpaceX itself admitted that they did not respond to ESAs inquiries when the situation got hot, citing paging system failure (which I call an absolute BS of an excuse). This article doesn't provide any new info, they're just re-iterating the same in a far more diplomatic language from an official rather than behind the scenes engineers POV.

So several ESA officials and their press release are lying due to 'diplomatic reasons', SpaceX is also lying and only the anonymous sources of Jonathan O'Callaghagn are accurate? I think you really need a reality check here.

Huh, what? Makes no sense. No, ESA did not lie, what they said would be technically truth even if they'd receive just 1 email with 3 words: "we won't move" it'd be sufficient to provide the information they needed. SpaceX obviously was saying truth as well, heck, they confirmed what ESA engineers said when admitted they did not communicate when the risk was known to be high enough to trigger CAM. The only thing inconsistent between them was SpaceX saying that they did not receive e-mails, while Krag claimed "excellent communication", but that's an obvious diplomatic language, so... whatever. Officials in press releases always sugar-coat everything, but I applaud your naivety if you think that every word put in press releases is an absolute and ultimate truth to be taken literally. And those you claim to be [bold]anonymous[/bold] sources are a real engineers that work daily in flight control, and however surprising it might be: they're far more open and honest to talk about issues behind the scenes than on an open stage, they are also by far more knowledgable than bullshitters on reddit. And yes, me working gives some insights you might not be aware of, hence why I know people that journo talked with were 100% truthful and I'm willing to defend them.

You are interpreting a fault in an automated email classifier as arrogant refusal to act on SpaceX’s behalf.

There’s no truth in that whatsoever, but plenty of lost tempers from old-space advocates who wish malice upon the newcomer who is not doing things “our way”. I have worked around engineers in a competitive space long enough to identify an ego issue when I see one.

Even the ESA doesn’t think “our way” makes sense anymore, thus their project to further automate the process of collision detection and avoidance, and the desire for better communication channels in the industry. Email doesn’t provide a reliable means of determining whether the content of a message has reached the people it needs to, or that a decision will be/has been made on how to react.

It appears that the miscommunication was the result of a ”bug” in SpaceX’s systems. That to me is a huge concern and points to gross incompetence, with 12,000 sats this could have gone worse. I also hope SpaceX learns from this and starts taking safety seriously.

I also hope all those who immediately jumped on this and accused ESA of faking this incident or conspiring to harm SpaceX for political/economic/anti-American reasons now realize that such talk is ridiculous.

Because bugs never happen and all other IT systems work flawlessly, always?

This is why they launched 60 experimental satellites and immediately deorbited five: to find problems and bugs in their systems. With 12,000 sats this won't happen because by then, they will have worked out most of the flaws.

And saying SpaceX needs to 'start taking safety seriously' or 'gross incompetence' shows that you really want to put SpaceX at fault here. It also seems like you have no background in engineering, or at least not IT, when you suggest that SpaceX's software developer are 'grossly incompetent' or that SpaceX does not take safety seriously because of an error in a new system they are testing right now

Also, the amount of people insisting this was the worst possible misconduct on SpaceX's side, like you, were in a great majority compared to people doing what you claim. Also, speculating on why ESA releases these statements is neither 'accusing ESA of faking the incident' nor 'accusing ESA of conspiring to harm SpaceX'. Speculation on intent is very much necessary, every time.

The bright side is that this happened when there were only 60 and it only happened for one satellite. The point here is when you find a weakness in your system you go and fix it and improve it. Things can go wrong and just saying "oh but there was this horrible problem, we're doomed!!" will not solve anything and I'd say is a bit pesimistic but that's just my opinion. Others may have a different one of course

You know great communication could also refer to anything other than the technical side of the equation? ESA already had a statement from SpaceX regarding their future course of action (none) and could plan accordingly.

Bad communication, how you claimed it happened, would have been an email from SpaceX saying 'F*ck you, we don't move. We don't care, if you crybabies are so afraid, move your own shitty satellite'. ESA's statements directly contradict this 'SpaceX bad' motion you present with each and every comment.

Not necessarily, they burned prograde to speed up and raise the orbit therefore adding more spatial and temporal separation. Without action the closest approach could have been closer than separation minus altitude gained.

So Object A is either remains on course or is moved manually. Object B will perform its task of avoidance either way.

Either way, Object B has the capacity to avoid Object A autonomously.

IF Object A and B do NOT have autonomous avoidance then the results are on HUMANS as it has been all along.

IF Object A and B both have autonomous avoidance then the software needs to have the ability to resolve duplicate avoidance maneuvers. This scenario, were both are effectively blind and deaf do in fact create an issue.

IF both rely on HUMAN information, then the results are HUMANS as it has been all along.

IF one or both have the ability to be aware of the intersection, then this should be a non issue.

​

In addition, this involved a swarm, if ALL swarm objects had the ability to be "aware" then the collective swarm could be used to negotiate the solution based on actual observation.

Because today, all that must be negotiated manually, by humans, over email. Which is fine if you handle maybe one intersection event per week. But when you have multiple constellations of several thousand, with a constant cycle of new satellites spiralling up and old satellites spiralling down to deorbit (or dead satellites drifting down more slowly) that is going to need a more formal communication and coordination method.

Well ESA is manual and Starlink is autonomous(? as in I am going on specs and not actual). Ergo Starlink would have invoked avoidance measures. I want to stress in this particular case I am not sure Starlink has autonomous avoidance software actively(full time) engaged.

Autonomous avoidance would only work for satellites you can actively negotiate manoeuvres with (i.e. other Starlink satellites) or possibly completely passive 'dead' objects (though as you'd be uploading intersection data anyway, that's practically manually command anyway). If you try and autonomously manoeuvre without communication you could end up in a Benny Hill-esque sequence of one satellite moving, then the other moves into closer intercept, then the other moves and the first moves back onto intercept, etc. At best you waste propellant with unnecessary burns, at worst you make a collision more likely.

Without finding the article, Starlink responds autonomously based on information, the same source ESA used. That being said, I am not sure the 60 have a full implementation, as I have not seen SpaceX state yes or no, only that some maneuvers have been tested.

one of the first 60 satellites recently launched in SpaceX’s mega constellation, planned to be a 12 000 strong fleet by mid-2020.

And in general I feel the article tries to push an agenda for automatic avoidance. I agree on the importance of it yet I feel they do so by making an ant into an elephant while putting SpaceX into a bad light.

But those articles were largely based on the ESA Tweet storm, so obviously there was something misleading about it—specifically, misleading in a way that made SpaceX look bad.

If the ESA Tweets were so unproblematic, why is there so much misinformation about SpaceX floating around in regards to this story? As usual.

And how is ESA “going easy” on SpaceX? What even is there to “go easy” on? They caused a complete non-story (a brief and inconsequential communication issue) to turn into a slew of misleading articles and misinformed internet commentary. It’s ridiculous.

The ESA tweets were not the cause of the misinformation. Almost all the misinformation can be attributed to Jonathan’s editorialising in his article about the issue. If you only read the quotes from named officials in Jonathan’s article, there’s a very different story to reading Jonathan’s words without those quotes.

That article spread like wildfire, which might be due to being retweeted by Loren Grush, who is followed by a lot of SpaceX fans and interested parties who might never have heard of Johnathan before this.

Need the different organizations to agree to a communications protocol for event identification and maneuver plan and acceptance. Protocols can include handshaking to assure agreement before action and clock timeouts indicating no negotiation after timeout. The backbone for communications is not so critical if it is by SQL or even automated emails into a web readable repository. One command could be to add a repository to the system so the system goes out to periodically read from all those who are registered. May require handing out certificates to confirmed entities so not anyone can connect in.
Really just takes one party to propose the base system and protocol which covers all required communications today or anticipated.
One command could be establish voice connection operator to operator in case there is an issue that can’t be addressed by the system protocol.
The system could be highly redundant that everyone can capture all communications and everyone can be calculating orbits and intersections and being double checked against each other. If one goes down, the others are all operating.

ESA is clearly pushing an agenda. Their bullet points are inaccurate or misleading at best. The satellite which has increasing overlap probability is not part of the constellation. Yes it was launched to be in the constellation, but the constellation had no overlap with ESA. This is a rogue satellite. This is clearly inaccurate. The next point of being on collision course is misleading. Instead the overlap probability increased and there was desire to increase spacing. I really dislike when politics are played like this. One expects more from an organization like the ESA even though SpaceX is eating their lunch.

For the first time, ESA has performed a 'collision avoidance manoeuvre' to protect one of its spacecraft from colliding with a satellite in a large constellation.

I can't say whether the first part is true, but the only nitpick here is that you could argue that Starlink44 is not part of a large constellation as it is halfway out of orbit. But you should interpret the 'in' not as an indication of location but rather an indication of belonging - so yes, a little bit misleading.

On Monday morning, the Agency's Aeolus Earth observation satellite fired its thrusters, moving it off a potential collision course with a SpaceX satellite in the Starlink constellation.

This is very much true, you can't even nitpick about 'collision course' here because of some misinterpration of probabilities, they put a 'potential' in there.

Constellations are fleets of hundreds up to thousands of spacecraft working together in orbit. They are expected to become a defining part of Earth’s space environment in the next few years.

You could point out that for example the Iridium NEXT constellation consists of less than 100 satellites, and only Megaconstellations have that size, but that would be minor nitpick.

Also, with Starlink, OneWeb, Kuiper etc. the part about a 'defining part of Earth's space environment' is very much true.

As the number of satellites in space dramatically increases, close approaches between two operated spacecraft will occur more frequently. Compared with such 'conjunctions' with space debris – non-functional objects including dead satellites and fragments from past collisions – these require coordination efforts, to avoid conflicting actions.

This is also true: The satellites in the constellations are all at the same height - causing a higher density at those heights. Also, conflicting actions is accurately cited as the mayor problem, something that isn't possible with dead space junk

Today, the avoidance process between two operational satellites is largely manual and ad hoc – and will no longer be practical as the number of alerts rises with the increase in spaceflight.

Correct - as proven by this incidence

“This example shows that in the absence of traffic rules and communication protocols, collision avoidance depends entirely on the pragmatism of the operators involved,” explains Holger Krag, Head of Space Safety at ESA. “Today, this negotiation is done through exchanging emails - an archaic process that is no longer viable as increasing numbers of satellites in space mean more space traffic.”

He is rightly criticizing the process of current negotations

ESA is proposing an automated risk estimation and mitigation initiative as part of its space safety activities. This will provide and demonstrate the types of technology needed to automate the collision avoidance process, allowing machine generated, coordinated and conflict-free manoeuvre decisions to speed up the entire process – something desperately needed to protect vital space infrastructure in the years to come.

This seems like a good proposal - not misleading and AFAIK not wrong.

​

So TLDR: the bullet points are completely correct and only at one point a bit misleading

The term 'potential collision course' is relatively well defined in spaceflight: due to the inherent inaccuracy in measuring orbit data, a collision can only be predicted with a probability <1. But even a seemingly small probability of 1e-4 is considered a big probability in spaceflight. You don't want to risk your nice research sat and years to decades of work to being proof of the law of large numbers. This is similar to idiots claiming that 1° C of global warming is irrelevant because it 'is not that much' or that reducing global warming by 0.000653 ° C (according to rightwing idiots, Germanies maximum share of global warming) is not worth it - it is a misinterpretation of data. By removing any scale and only showing some arbitrary number to then argue that this number is small is intelectually dishonest.

And even if they were pushing an agenda, it would be about their automated collision avoidance system, not some personal vendetta against SpaceX. This is also strongly indicated by their last to bullet points, the most detailed of the bullet points.

Of course, the media won’t write any articles about how ESA later softened their stance, and we’ll continue to encounter people online who say that SpaceX refused to move their satellite which led to a “near disaster” (thanks a lot, Greg Wyler).

And their original Tweet storm (and the accompanying Forbes article) was egregiously misleading—portraying SpaceX as unresponsive and “refusing” to move.

You can parse the Tweet storm and say that it is factually accurate, but given the impression it gave, even to SpaceX fans and journalists who wrote inaccurate articles based on it, it was obviously misleading. I don’t think it requires a tinfoil hat to suspect that this was not an accident.

No, the initial Tweet storm was in no way negative about SpaceX. Yes, naming the satellites' operator by name was unusual but not out of the "intern managing social media wanted variation" kind of unusual. I still think that the author of the initial tweets from ESA did not expect this to get picked up by the Musk haters so hard. I think these tweets' influence has been underestimated, which is why we only see the press release "correcting" the misinformation today (or yesterday?) and not together with the initial tweets.

The Forbes article and the 'sources inside ESA' cited by Jonathan O'Callaghagn are complete bullsh*t. But if you ignore those 'sources' and only look at the official statements, this very much looks like accidental bad PR for SpaceX. If they really wanted to throw shade, they would already start with a press release, because a Tweet storm is (or should be) not credible enough to start the media machinery if the possibility of an official press release is present.

Also, did you not see the German article cited as the first source to relieve SpaceX? The one with actual quotes by an actual ESA employee?

But didn’t the ESA rep cited in the German article totally contradict part of the Tweet storm when he said that both parties had already previously agreed on a course of action if the risk assessment increased? In contrast, the ESA Tweets claimed (or at least strongly implied) that they were forced to act unilaterally due to SpaceX’s unresponsiveness.

If both parties had already agreed on a course of action, how was a brief and inconsequential communication problem with SpaceX even worth mentioning? And why couldn’t ESA keep its story straight? Seems like the hallmarks of FUD.

The tweet storm does not imply anything like this. Also, the part about 'agreeing Aeolus would move' is sadly no direct quote from Holger Krag, but followed by one. So what this sounds like is they actually communicated, agreed no action was necessary and if it would become necessary, Aeolus would move.

But what I think is more likely is that without further correspondence, you have to assume the other party remains on their stance, and you should not change your stance without further correspondence. So ESA already had SpaceX saying they would not move - due to unprecise data, not because they wanted Aeolus to move - but because they already had a statement, any change to this statement would need to be communicated.

Maybe this thing is more confusing than I think, maybe the new article is incorrect/unprecise and I am correct, we don't know

Its totally possible that there there are different personalities within ESA, some of which play on emotions, and others being more objective. Its also possible that they collectively saw how embarrassing the initial tweets could later become and did some fast back-pedaling.

ESA is now on a more consensual terrain and saying something constructive.

Whatever the long-term solution, let's hope they don't depend on any single source for primary input data and the system is overseen by an international entity.

A flight control system is an obvious target for all sorts of espionage/sabotage, so it needs to be built around numeric signatures and timestamping with analysis being done in parallel in different countries and cross-checked. Parts of the system could be autonomous onboard satellites, which then ask for maneuver permission from the international network. Financial compensation for maneuvering costs could be built in. Having defined a single planetary standard, this architecture should be reproducible around the Moon and Mars.

Possibly (charitably) honest but not competent. SpaceX not moving Starlink44 appears to not have even been a point of contention between ESA and SpaceX (someone has to move and someone has to not move, or you risk moving into each other) but a layman may interpret that incorrectly as a refusal to cooperate rather than as arranged cooperation.